Relationship between Salmonella translocation patterns and immune responses in orally inoculated pigs

Authors: Broadway, Paul; Carroll, Jeffery - Jeff Carroll; Sanchez, Nicole; GART, ELENA - Texas A&M University; BRYAN, LAURA - Texas A&M University; GOLD, RANDI - Texas A&M University; YANG, CHING-YUAN - Texas A&M University; LAWHON, SARA - Texas A&M University

Submitted to: Journal of Animal Science Supplement
Publication Type: Abstract Only
Publication Acceptance Date: 3/22/2015
Publication Date: 7/1/2015
Citation: Broadway, P.R., Carroll, J.A., Sanchez, N.C., Gart, E.V., Bryan, L.K., Gold, R.M., Yang, C., Lawhon, S.D. 2015. Relationship between Salmonella translocation patterns and immune responses in orally inoculated pigs. Journal of Animal Science Supplement. 93 (E-Supplement 3):633-634, Abstract#1042.

Interpretive Summary:

Technical Abstract: Salmonella is a pathogen of interest with broad implications ranging from animal health to food safety. Translocation patterns of Salmonella from the gastrointestinal tract to peripheral tissues have not been fully elucidated. Also, the mechanisms by which immunological responses influence translocation and fecal shedding are not fully understood. The objective of this study was to determine the translocation patterns of orally inoculated Salmonella in response to changes in immune biomarkers. Male pigs (n=12; 6.1 ± 2 kg) were orally inoculated with 4.7x109 CFU of Salmonella Typhimurium. Whole blood samples were collected and analyzed for serum cortisol concentrations and complete blood counts. Fecal samples were collected daily from -1 to 3 d relative to the bacterial challenge on d 0. At 72 h post-inoculation, animals were humanely euthanized and tissues were collected to determine the presence of the inoculated Salmonella [messenteric lymph node (LN), subiliac LN, liver, spleen, kidney, and gallbladder]. There was a tendency (P=0.06) for fecal shedding quantity to be similar to mesenteric LN Salmonella concentrations at 72 h. There was no interaction (P>0.05) between the presence of Salmonella in LN and any of the immune parameters measured. Subiliac LN Salmonella concentrations were highly correlated (P=0.0001; r=0.99) with liver Salmonella concentrations. Fecal shedding at d 3 was negatively correlated with kidney and gallbladder Salmonella concentrations (P=0.04). Cecum concentrations of Salmonella were negatively correlated with white blood cell (P=0.02 r=-0.72) and neutrophil (P=0.0003) counts. These data suggest that orally inoculated Salmonella may translocate to tissue not only within the gastrointestinal tract but to organs and peripheral tissues such as musculoskeletal LN. Additionally, negative correlations between immune biomarkers and Salmonella migration suggest that translocation of Salmonella may be inhibited following the peak immunological response. Further information is needed to fully elucidate the mechanisms by which pathogens interact with their host and how an immune response alters migration patterns.